remove clouds.yaml files when running clean.sh

There have been a few reported errors of folks running into
issues with old clouds.yaml files that linger around. Remove
these if the user runs clean.sh.

1. http://lists.openstack.org/pipermail/openstack-dev/2016-January/084283.html
2. https://ask.openstack.org/en/question/84825/glance-upload_image-fails-in-latest-devstack/
3. https://ask.openstack.org/en/question/86071/devstack-installation-failure/

Change-Id: I618ea8e27b49af360c905df85af06d9b1eef8407

Author: Steve Martinelli

clean.sh

@@ -137,6 +137,7 @@ FILES_TO_CLEAN=".localrc.auto .localrc.password "
 FILES_TO_CLEAN+="docs/files docs/html shocco/ "
 FILES_TO_CLEAN+="stack-screenrc test*.conf* test.ini* "
 FILES_TO_CLEAN+=".stackenv .prereqs"
+FILES_TO_CLEAN+="/etc/openstack/ ~/.config/openstack"
 
 for file in $FILES_TO_CLEAN; do
     rm -rf $TOP_DIR/$file